The invention relates generally to a semiconductor device and method of making thereof and more specifically to a three dimensional diode nonvolatile memory array and method of making thereof.
Nonvolatile memory arrays maintain their data even when power to the device is turned off. In one-time-programmable arrays, each memory cell is formed in an initial unprogrammed state, and can be converted to a programmed state. This change is permanent, and such cells are not erasable. In other types of memories, the memory cells are erasable, and can be rewritten many times.
Memory cells may also vary in the number of data states each cell can achieve. A data state may be stored by altering some characteristic of the cell which can be detected, such as current flowing through the cell under a given applied voltage. A data state is a distinct value of the cell, such as a data ‘0’ or a data ‘1’.